Quick Load question

[M99]

I'm a new user of Quick Load. Lots of high end data it shows for both standard cartridges and our Competition Loads. However, I'm starting to wonder how accurate some of their calculated data actually is.

With my 7 SAUM, I carefully made all the measurements possible and input that data. Their calculations showed that my load should exit the muzzle at only about 2750 FPS and drop 24 MOA at 1,000 Yards starting at a 200 Yard Zero.

However, my observed results are 2900 FPS and a 21 MOA drop, with considerable higher pressure than what they calculate.

I've gone over the data and results many times. I'm wondering if others have the same experience with their calculated results being that much different than actual observed results?

 

[jepp2]

I'm wondering if others have the same experience with their calculated results being that much different than actual observed results?

To make QL predictions match my actuals, I use the recommendations in the attached file. If I don't, the results can be significantly different. Using the new Ba value for my powder lot, it significantly improves the predictions.

That is one of the many reasons I now use GRT instead of QL. By entering my measured velocities, GRT adjusts the burn rate, and the node recommendations are based on that. In QL, you have to do all that outside the program.

 

[Ned Ludd]

Powder burn rates can vary, sometimes markedly, depending on pressure, temperature, etc. There is no feasible way for a program such as QuickLoad to store all the possible for burn rates for a single powder that have been adjusted to every possible combination of cartridge shape/size, temperature, pressure, etc., let alone for hundreds of different powders. So they provide a single standardized burn rate value (Ba) and allow the user to change it as needed.

To carry out what I refer to as "calibrating" the program to a given rifle setup, one needs to enter all the pertinent load inputs (COL, bullet oal, case trim length, case volume, temperature, charge weight, etc.), then adjust Ba such that the predicted velocity exactly matches an average velocity actually determined for that specific load/rifle setup using a chronograph. There are certainly caveats to this process, such as if one has to change the Ba by more than certain amount. I would suggest reading the instruction manual. It's sometimes a little tedious to find things in the electronic format, but the information you seek is in there. Further, "calibrating" QuickLoad is often not a single, one-time step, but an ongoing process that needs to be carried out repeatedly over time in order to obtain the best outputs/predictions.

 

[M99]

Thank you both for that great help and information. I will certainly follow it. I did enter all the measured items for my Cartridge, Brass, Bullet, and so on, but did not realize I had I had to calibrate it for my specific situation. I was very much surprised to see the predicted FPS 150 FPS lower than what I was measuring and seeing on target. I'll do a lot of reading and follow those instructions what were attached here.

 

[Jager]

I'll just emphasize that cartridge case volume is a critical input for getting accurate results out of QL. The program has a default number for every cartridge in its database, but because of the large variation in case volume between different headstamps - and even, sometimes, between lots within a given headstamp - that default will rarely exactly match a shooter's own lot of brass.

Carefully measuring (with water) several samples of your brass will significantly improve the precision of the program.